Process of preparing 2, 4-dihydrobenzenesulfonic acid



' chloroform or ether or similar inert diluents for Patented Nov. 8, 1949 I e 2 ,487,586

UNITED STATES EATENT F *MGE ;;'-2J487,58B ZRRGUESS' mZZBIH YDRO- IBENfiENESULFONICiAEID WillafiPDLPtersonfiflastonff'a assignor to Genel-a1 -minute 58; Tilm Corporation, New York,

31., woorpumtiornof Delaware No Drawing. i'iflpjilicationl lflloven'lbera28,5394,

' Q'Se'riil No. $889655 H mfilaiurs. (015260-312) B 2 This "invention relates to "a *process for rhydroxybenzenessulfonio acid-can be-obtainedrn 'sfilfonatirm'"offij iidihfdroxybenzene"fresorcinelt .pure form hyaasratherasimple processtwhich adoes and more particularly, it-relates t th .prcducnot requirewdecolorization,l-lsalting-eout orevapit'i'on :o'f the 'mono-sulfonic i'ac'i'd derivative :of oration in order torecover the pure monosulfonic resoremdl, .5 acid resorcinol. Thisprocessconsists in reacting Themono-sulfonlvacid"deiivritivefdfiresorcmfiol ithe. chlorsulronicaacidsandrresoreincl::inithe. preshas i -been .iproduced .-:bytreatment "dffin'ely ".powfelifce tofcn-itro: benzene-z ascaminertadthrentiforrtlue dere'd 'resorcintSrwfth "an"equimol'ec1'flar' amount reactants. of concentrated sulfuric 'acid('66'B'.')irf"tlrecold. 33118 reaction :of zehlorsuliomczacid rand Iresorln this pnocess themactionmixture is ewgd l.0 oinol, awhich c'proceedslin accordance with time in "water "and the resfflting solution saturated foregoing :'equations,ssets=;up sareompetition shewith bariumeeanbgnate, iIt.-.-is-.-then decolorized etween;then"esorcinoleanditheoinitiaillynfermedmewith charcoal arid evapora'te'dto "dryness in order sorcinol monosulfonic acid for the residual ch lo =to=ol ita7ln =the'banium sd lts df rresor'cirnil monosulfonic acid as long. as zboth'sresorcinol products summic acid This process igsgilibjetito ithe m; .15 are present in the reaction mixture. When the advantagesnsesultiugthe.:necessity of using reactio-n -lS CaTI *i6d "-Out in the presence of nitro concentrated sulfuric acid producing as it doesa be e a t e dllnentfithinlt'illlyformed rnonodiscoloration which must later be removeilhry "slilfonic acid' derivativeof resorcinol-precipitates *treatment with"charcoal. "Ita-lsohnvolvesit'lmeout as rast as it-isronnedhuete the i s i it ii r tion-"m nder to separate out the"monosfilforiiceidhaMitrdbenzene. Consethe salts of the resorcinol mono-sulfonic acid. yfi ueh e%ction#2 is t'he s'tro o' The sulfonation of resorcinol and related prodthe Competing reactions y e onosulfonic ucts by reaction with chlorsulfonic acid has been acid derivative Will he formed as a P uc nce suggested. However, only the disulfonated prodit is p p d ut and removed from the ucts or, at best, mixtures of the di-sulfonated and sphere of reaction as fast as it is formed. mono-sulfonated derivatives of resorcinol have This process is carried Out y mixing e her 01' been obtained by this 'method. Thus, wh both of the reactants with the nitro benzene chlorsulfonic acid is reacted with resorcinol in diluent and addin the o e reactant to the soluthe proportion bf 2170 1 in carbon disulfide as 3, tion Of the other in the diluent. It has been solvent at 0 C. or at room temperature, resorcinol found most convenient to add a mixture of the 4,6-disulfonic acid is formed. If equimolecular chlorsulfonic acid and the diluent to a mixture proportions of the chlorsulfoni id d resorof resorcinol and the diluent. It is also preferable cinol are reacted in the same solvent, or in to react appr imat ly eq m flar amounts of the chlorsulfonic acid and resorcinol. The the reactants, a mixture of the disulfonated 3; rate of mixing the rea ppears to have resorcinol and the monosulfonated resorcinol will little effect O the P u on of the monosulbe obtained in accordance with the followin fonated product and has no appreciable effect on reactions; the yield. The temperature at which the reaction is carried out appears to have only slight on 0H 7 (1) 4 effect on the yield and none on the purity of the product. The reaction has been carried out at 015 can temperatures ranging from 15 C. to 75 C. With- OH OH out noticeable effect on either the yield or the purity and there appears to be no appreciable difference in the yield or purity of the reaction product whether the temperature is allowed to 0H rise during the reaction or is held at a constant temperature of, for example, 15 C. or 60 C.

HOaS- Except for some change in the yield, the volume C1S0=E of the nitro benzene diluent does not appear to OH OH have any effect on the reaction. It has been A found that the larger the volume of the diluent 303E 03H the lower the yield of resorcinol monosulfonic It has now been discovered that the monoacid. On the other hand, suflicient diluent should sulfonic acid derivative of resorcinol, i. e., 2,4 -dibe used to insure at least partial solution of the SOQH Example I To a solution of 660 parts of resorcinol in 3320 parts of nitrobenzene at 40 C., are added with stirring 699 parts of chlorosulfonic acid in 415 parts of nitrobenzene in 2-3 minutes, during whichtime the temperature rises to 60-65 0. Upon cooling to 5 C., a light tan solid of high purity, 2,4-dihydroxybenzene-sulfonic acid, separates in practically quantitative yield.

Example II To a mixture of 220 parts of resorcinol and 1660 parts of nitrobenzene, 232 parts of chlorosulfonic acid in 415 parts of nitrobenzene are added rapidly with agitation; the temperature being maintained at 1520 C. by external cooling. A practically quantitative yield of pure 2,4-dihydroxybenzene-sulfonic acid is obtained as a light tan solid. Example III To a mixture of 220 parts of resorcinol and. 1245 parts of nitrobenzene at room temperature, a mixture of 235 parts C1SO3H iI1 415 parts nitrobenzene is slowly added with stirring over a period of 3 hours. rises from room temperature to 40 C. Upon The temperature of the reaction cooling the reaction mixture, 370 parts of light tan, extremely pure 2,4-dihydroxybenzene-sulionic acid are isolated by filtration.

Having now particularly set forth my invention and having illustrated the best manner in which to perform it, what I claim is:

1. The process of preparing mono-sulfonated resorcinol which comprises reacting chlorsulfonic acid and. resorcinol in nitrobenzene and separating the resorcinol mono-sulfonic acid product from the reaction mixture.

2. The process of preparing mono-sulfonated resorcinol which comprises reacting approximately equimolecular amounts of chlorsulfonic acid and resorcinol in nitrobenzene and separating the resorcinol mono-sulfonic acid product from the reaction mixture.

' 3. The process of preparing mono-sulfonated resorcinol which comprises mixing a solution of chlorsulfonic acid in nitrobenzene and a solution of resorcinol in nitrobenzene while stirring, cooling the reaction mixture and separating the resorcinol mono-sulfonic acid product therefrom.

4. The process of preparing mono-sulfonated resorcinol which comprises adding a solution of chlorsulfonic acid in nitrobenzene to a solution of resorcinol in nitrobenzene while stirring, cooling the reaction mixture and separating out the resorcinol mono-sulfonic acid product'by filtration.

- WILLARD D. PETERSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,452,481 Baddilz et a1 Apr. 1'7, 1923 1,716,082 v Parmalee June 4, 1929 

